In order to achieve the international objectives surrounding projected global warming trends through 2100, climate change observers contend, economies worldwide must reduce their greenhouse gas (GHG) emissions significantly in all sectors. Recognizing how emissions discipline applies to the construction industry, Germany’s Liebherr Group is working on new, efficient drive concepts for its concrete delivery and earthmoving equipment. The manufacturer enlisted Frontier Economics, a consulting firm with offices in Berlin and six other major European cities, to conduct a life cycle analysis of GHG emissions of typical construction machines equipped with various drive technologies. Investigators determined how much carbon dioxide gas arises from production to operation through to the recycling of the machines. The aim of the analysis was to comprehensively calculate the emissions of the machines and their drives in order to be able to recognize and assess how GHG emissions can be most effectively reduced.
It is important for stakeholders to look at the overall life cycle of the machines, Frontier researchers affirm. The life cycle factor ranges from the mining and transport of the raw materials to production and the actual operation of the machine to the disposal and recycling. “Emissions analyses are generally limited to the operating phase. This is not enough for our products because greenhouse gas emissions also occur in the upstream and downstream phases of construction machines’ lifecycles,” says Liebherr-International AG Director Stephen Albrecht. “To get a complete picture, we examined all stages of the life cycle, including the production of energy and provision of the infrastructure.” Results are combined in a so-called product carbon footprint, which describes the emissions of a product throughout the entire life cycle, he adds.
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The Frontier study examined three types of construction machines: mobile cranes, truck mixers and wheel loaders. As evidenced by the collected data, the three types require different drive technologies in order to reduce as much emissions as possible due to their different performance requirements: For truck mixers, electric drives make the biggest contribution to emissions reductions provided they use 100 percent renewable electricity for charging.
For mobile cranes, operation with hydrotreated vegetable oil (HVO) shows the biggest savings potential. Important is that the HVO is certified to be produced from plant and food waste, for example, and does not contain palm oil. Hydrogen made from CO2-neutral sources follows in second place. In the long term, operation with hydrogen seems optimal as the availability of HVO in the vast quantities required cannot yet be predicted. However, until the required hydrogen infrastructure and drive technologies are mature, HVO delivers the best results as an interim technology, particularly in existing fleets with combustion engines. Wheel loaders should be operated either with a battery electric drive charged with renewable electricity, or with e-fuels. “The results of the life cycle analysis show that there is no uniform solution for climate-neutral drives of construction machines,” Liebherr’s Albrecht observes, adding that the company therefore relies on a technology-neutral approach and can thus reduce emissions as much as possible depending on the machine and the application.
A look at the Liebherr product portfolio, which includes 13 product segments and is particularly broad especially in the area of construction machines, illustrates what leads company engineers to compare various drive technologies. The smallest machines have a power output of 30 kW, the largest have a power output of more than 3,000 kW. All these machines must perform reliably in completely different conditions in diverse applications.
“A wheel loader on an urban construction site, for example, is exposed to different conditions than a mobile crane used in the construction of wind turbines,” explains Albrecht. “The former can often be powered by electricity. In contrast, infrastructure projects in rural areas often lack the necessary power supply for an electrical connection. In addition, more energy is often required than can be provided with a battery-operated electric drive.”
Liebherr engineers work with the wide range of climate-neutral fuels and drive technologies, from certified HVO to e-fuels made from green electricity, water and CO2, battery electric drives and hydrogen drives, be it hydrogen combustion engines or hydrogen fuel cells. At the moment HVO is particularly interesting for the manufacturer because it is an already available, interim technology. It has the advantage that it can be used in older construction machines with diesel engines. Such machines are often in use even longer in many regions of the world, where they continue to raise GHG emissions levels. Emissions can also be reduced significantly with HVO as a diesel admixture.
Based on the results of the life cycle analysis, Liebherr favors adopting a technology neutral approach in the transformation of the construction industry. “Effective climate targets and incentives for the construction machinery sector must enable technological diversity so that the most environmentally friendly technology can be used depending on the performance requirements,” Albrecht observes. In this light, he adds, battery electric should not be viewed as a universal solution, but as one important technology in the future drive mix. Apart from electric drives, it is just as important to closely monitor the topic of hydrogen. The regulatory conditions for producing hydrogen and e-fuels, which are made from renewable sources, must also be established. After all, the interaction of all these technologies allows optimal solutions to be created for all application scenarios in the construction machinery sector.
Liebherr’s intensive research and development work is already bearing fruit, as reflected in the performance of several construction and mining machines with zero-emission drive technology. The all-electric truck mixers ETM 1005 and ETM 1205, for example, run on batteries are charged between travel to and from the jobsite or overnight.
Liebherr also promotes the use of HVO in its factory in Ehingen, among other places. Since September 2021, all new mobile and crawler cranes produced there are filled with one hundred percent HVO before delivery to customers, and are also operated with HVO for on-site crane acceptance tests and test drives. The Liebherr factory in Kirchdorf a.d. Iller has followed suit: HVO has been used for first filling and acceptance tests of earthmoving and material handling machines since January 2022. The factories’ internal logistics are also changing over to the climate-neutral fuel.